1. Field of the Invention
This invention pertains generally to dual-band resonant devices, and more particularly to compact dual-band resonant devices formed from anisotropic metamaterial.
2. Description of Related Art
Wireless communication capability has become a built-in function in almost all modern hi-tech products in the past few years. In particular, dual-band or multi-band operations such as GPS/K-PCS and PCS/IMT-2000/Bluetooth, which are able to provide multiple functions within a single device, are receiving increasing attention. In the radio-frequency (RF) front-end module of such wireless multi-band systems, the antennas which can support multi-band transmitting and receiving are one of the critical elements needed to construct. Generally, multi-band operation is achieved by creating various configurations to resonate at different frequencies required for a specific application in a single radiating device. For example, a dual-band antenna has been realized by slightly changing the shape of a rectangular patch antenna and exciting two frequency modes with two feeding lines. A planar inverted f-antenna (PIFA) is another popular antenna that can achieve multi-band operation.
In addition, due to the decreasing available space for the wireless module, shrinking the antenna size is another important issue considered in the design specification. One approach to reducing antenna size, is to use metamaterials in the design and construction of the antennal. As we have previously demonstrated, because of their unique electromagnetic properties metamaterials can be applied to antenna applications where the size of the antenna need to be substantially reduced (C. J. Lee, K. M. K. H. Leong, and T. Itoh, “Design of resonant small antenna using composite right/left-handed transmission line,” Antenna and Propagation Society Symposium, July 2005).